AoE4 Generated Map Function: Circle Outline

circleOutline.lua

--draws a circle outline
--copy and paste code to preview at https://aoe4.app/

--radius (float) the radius of the circle
--centerCoord (table) x y coordinates of the circle center
--pickedTerrain (str/var) the terrainType name to draw
--implodeWidth (float) experimental and can produce interesting results when increasing
--iterations (int) the number of circle iterations to draw, used in conjunction with strokeSpacing
--strokeWidth (int) the circles outline width
--strokeSpacing (float) the amount of spacing between circles if there are multiple iterations set
function circleOutline(radius, centerCoord, pickedTerrain, implodeWidth, iterations, strokeWidth, strokeSpacing)
    
    --checks to see if coords exist in table
    --used to prevent out of bounds areas from being set
    local function isInTable(searchTable, row, col)
        if (searchTable[row] ~= nil and searchTable[col] ~= nil) then
            result = true
        else
            result = false
        end
        return result
    end
    
    print("--- BEGIN CIRCLE OUTLINE ---")
	
    for i = 0, strokeWidth do
		
	--increase the radius with each pass for a thicker stroke
	radius = radius + i * 0.125
        
        for r = 0, math.floor(radius * math.sqrt(0.5)) do
            d = math.floor(math.sqrt(radius * radius - r * r) - implodeWidth)
            
            if (isInTable(terrainLayoutResult, centerCoord.row - d, centerCoord.col + r)) then
                terrainLayoutResult[centerCoord.row - d][centerCoord.col + r].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row + d, centerCoord.col + r)) then
                terrainLayoutResult[centerCoord.row + d][centerCoord.col + r].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row - d, centerCoord.col - r)) then
                terrainLayoutResult[centerCoord.row - d][centerCoord.col - r].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row + d, centerCoord.col - r)) then
                terrainLayoutResult[centerCoord.row + d][centerCoord.col - r].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row + r, centerCoord.col - d)) then
                terrainLayoutResult[centerCoord.row + r][centerCoord.col - d].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row + r, centerCoord.col + d)) then
                terrainLayoutResult[centerCoord.row + r][centerCoord.col + d].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row - r, centerCoord.col - d)) then
                terrainLayoutResult[centerCoord.row - r][centerCoord.col - d].terrainType = pickedTerrain
            end

            if (isInTable(terrainLayoutResult, centerCoord.row - r, centerCoord.col + d)) then
                terrainLayoutResult[centerCoord.row - r][centerCoord.col + d].terrainType = pickedTerrain
            end
        
        end
        
    end
    
    --creates expanding rings based on number of iterations
    --stroke spacing increases the distance between rings
    if (iterations > 1) then
        circleOutline(radius + (strokeSpacing + 1), centerCoord, pickedTerrain, implodeWidth, iterations - 1, strokeWidth, strokeSpacing)
    end

end

centerCoord = {}
centerCoord.row = mapHalfSize
centerCoord.col = mapHalfSize

--circle outline params
--adding 0.25 increments to radius and strokeSpacing can produce better looking results
circleRadius = 5.25
implodeWidth = 0
iterations = 2
strokeWidth = 2
strokeSpacing = 2

--the circle outline!
circleOutline(circleRadius, centerCoord, tt_swamp, implodeWidth, iterations, strokeWidth, strokeSpacing)